10 ANNIVERSARY ADDRESS. 
especially of London, which are not presentin Australia. What- 
ever these may be, they have eluded chemical analysis, and they 
may prove to be of importance in judging of the purity of an 
atmosphere. If it should prove so, it will be rather curious that 
we are obliged, after all, to use our eyes to see what we breathe. 
Whether these lines indicate substances which make the difference 
between health and disease, cannot yet be decided; but there is 
no doubt that the air at times contains the cause of disease in 
such a subtle form as to elude all the ordinary modes of investi- 
tion. 
Astronomers have this year to chronicle another temporary 
star, showing spectroscopic evidence of a sudden and extraor- 
dinary increase in its temperature. The new star, which was 
-discovered on the 24th of November last by Professor Schmidt, 
of Athens, was of the third magnitude, and not far from Rho 
Cygni. Onthe 2nd December it was spectroscopically examined 
by M. Cornu, of Paris, and found to give a spectrum of bright 
lines, the positions of which were fortunately determined, 
although the star was then only of the fourth or fifth magnitude. 
‘Eight lines were measured, and five of these were found to be 
almost exactly coincident with C, D, E, F, and G of the Frauen- 
hofer lines. So that the principal lines in the star spectrum 
coincide with the brightest lines of the sun’s chromosphere seen 
in total eclipses, which seems to prove that the materials of the 
star were ina state of incandescence. It will be remembered 
that a still more remarkable star, giving a bright line spectrum, 
appeared in 1866—T. Corone Borealis—and in ten days faded 
beyond the limits of unaided vision. 
Mr. Crookes seems disposed to give up the theory that the 
radiometer motions, or any part of them, are due to light only, 
for he says :—*T have recently succeeded in producing such a 
complete exhaustion in the radiometer that I have not only 
reached the point of maximum effect, but gone so far beyond it 
_ that repulsion nearly ceases, and the results I have thus obtained — 
seem to show conclusively that the true explanation of the 
action of the radiometer is that given by Mr. Johnstone Stoney, 
v 
